Twitter tumbles on concerns about hacking activity

Twitter shares fell almost 7 percent on Monday after the company said it was investigating unusual traffic that might be from state-sponsored hackers and, in what appeared to be an unrelated issue, a security firm said hackers used the platform to try to steal user data.

Twitter said in a blog that it discovered suspicious traffic to a customer-support forum while investigating a security bug that exposed data, including users’ phone country codes and details on locked accounts. It said the bug was fixed Nov. 16.

Twitter observed a large amount of traffic to the customer support site coming from individual internet IP addresses in China and Saudi Arabia.